The present invention relates to silver halide color photographic materials that are improved in image keeping quality and color reproduction.
Color print papers and other color photographic materials that are intended for direct viewing have conventionally adopted the combinations of yellow, magenta and cyan couplers for the purpose of forming color dye images. Extensive efforts have been made in order to improve the lightfastness of color dye images produced from these couplers so that they can be stored for use over many years.
However, the results of these efforts are not completely satisfactory in meeting the user's demand for preventing the fading or discoloration of dye images in color photography so that he can store image of high quality for an almost indefinite period. As for the keeping quality of images in the dark such as on albums, significant improvements have recently been accomplished in the art as typically exemplified by "Konica Color 100-Year Print", thus making it possible to store photographic images for an acceptable long period. On the other hand, the lightfastness of images, namely, their keeping quality under exposure to light, is still unsatisfactory and needs further improvements. In particular, magenta dyes have lower lightfastness than yellow and cyan dyes and considerable efforts for improvement have been made.
Recently developed pyrazoloazole base magenta couplers are characteristically different from the heretofore used 5-pyrazolone base magenta couplers in that the color dyes do not have an unwanted absorption at wavelengths near 430 nm and that, hence, they are essentially advantageous from the viewpoint of color reproduction. However, it is known that magenta dyes produced from pyrazoloazole base magenta couplers have lower lightfastness than those produced from 5-pyrazolone base magenta couplers, and many techniques for improvement have so far been proposed. To name a few, Japanese Laid-Open Patent Application (kokai) Nos. Sho 56-159644, 59-125732, 61-145552, 60-262159, 61-90155 and Hei 3-39956 proposed the use of phenolic or phenylether base compounds; Japanese Laid-Open Patent Application (kokai) Nos. Sho 61-73152, 61-72246, 61-189539, 61-189540 and 63-95439 proposed the use of amine base compounds; Japanese Laid-Open Patent Application (kokai) Nos. Sho 61-140941, 61-145554, 61-158329 and 62-183459 proposed the use of metal complexes; and Japanese Laid-Open Patent Application (kokai) No. Hei 2-100048 proposed the use of inclusion compounds or hetero cyclic compounds. However, when these compounds are put to actual use, various problems can take place, as exemplified by a drop in the color densities of couplers, the occurrence of color staining during prolonged storage, color contamination due to coloring by the added compounds per se, unwanted changes in color, and deterioration in the dispersibility and time-dependent stability of coupler-containing dispersions. The techniques described above have proved to be very effective in improving the lightfastness of magenta dyes but the state of the art is such that the thus improved lightfastness of magenta dyes is still poor compared to that of yellow and cyan dyes and, in the fading process, the color balance of image is upset and the color of the actual picture shifts toward the yellow or cyan side, thereby causing quite unnatural changes in color. As another approach, a branched alkyl group having great steric hindrance can be substituted on the pyrazolotriazole skeleton with a view to improving the lightfastness of the magenta dye and this idea is taught in Japanese Laid-Open Patent Application (kokai) No. Sho 61-65245. This technique is effective in providing improved lightfastness but, at the same time, new problems arise such as the broad absorption of light by the resulting dye and the drop in the efficiency of color formation. Hence, the development of a more effective approach is strongly needed for the particular purpose of improving the lightfastness of magenta dye images.